1
|
Han Q, Su Y, Smith KM, Binns J, Drummond CJ, Darmanin C, Greaves TL. Probing ion-binding at a protein interface: Modulation of protein properties by ionic liquids. J Colloid Interface Sci 2023; 650:1393-1405. [PMID: 37480654 DOI: 10.1016/j.jcis.2023.07.045] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/25/2023] [Revised: 07/05/2023] [Accepted: 07/08/2023] [Indexed: 07/24/2023]
Abstract
Ions are important to modulate protein properties, including solubility and stability, through specific ion effects. Ionic liquids (ILs) are designer salts with versatile ion combinations with great potential to control protein properties. Although protein-ion binding of common metals is well-known, the IL effect on proteins is not well understood. Here, we employ the model protein lysozyme in dilute and concentrated IL solutions to determine the specific ion binding effect on protein phase behaviour, activity, size and conformational change, aggregation and intermolecular interactions. A combination of spectroscopic techniques, activity assays, small-angle X-ray scattering, and crystallography highlights that ILs, particularly their anions, bind to specific sites in the protein hydration layer via polar contacts on charged, polar and aromatic residues. The specific ion binding can induce more flexible loop regions in lysozyme, while the ion binding in the bulk phase can be more dynamic in solution. Overall, the protein behaviour in ILs depends on the net effect of nonspecific interactions and specific ion binding. Compared to formate, the nitrate anion induced high protein solubility, low activity, elongated shape and aggregation, which is largely owing to its higher propensity for ion binding. These findings provide new insights into protein-IL binding interactions and using ILs to modulate protein properties.
Collapse
Affiliation(s)
- Qi Han
- School of Science, STEM College, RMIT University, Melbourne, VIC 3000, Australia
| | - Yuyu Su
- School of Engineering, STEM College, RMIT University, Melbourne, VIC 3000, Australia
| | - Kate M Smith
- Australian Synchrotron, Australian Nuclear Science and Technology Organisation, 800 Blackburn Road, Clayton, VIC 3168, Australia; Swiss Light Source, Paul Scherrer Institute, Forschungsstrasse 111, Villigen-PSI, 5232 Villigen, Switzerland
| | - Jack Binns
- School of Science, STEM College, RMIT University, Melbourne, VIC 3000, Australia
| | - Calum J Drummond
- School of Science, STEM College, RMIT University, Melbourne, VIC 3000, Australia.
| | - Connie Darmanin
- La Trobe Institute for Molecular Science, Department of Mathematical and Physical Sciences, School of Computing Engineering and Mathematical Science, La Trobe University, Bundoora, VIC 3086, Australia.
| | - Tamar L Greaves
- School of Science, STEM College, RMIT University, Melbourne, VIC 3000, Australia.
| |
Collapse
|
2
|
Kanzaki R, Kodamatani H, Tomiyasu T. Proton Thermodynamics in a Protic Ionic Liquid, Ethylammonium Nitrate. Chemistry 2019; 25:13500-13503. [PMID: 31454440 DOI: 10.1002/chem.201903485] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/30/2019] [Indexed: 11/11/2022]
Abstract
In order to investigate the proton solvation state in protic ionic liquids (PILs), ten acid dissociation enthalpies and entropies of eight compounds were determined in ethylammonium nitrate (EAN). Regardless of the nature of the compound, 24 kJ mol-1 larger enthalpy and 65 J mol-1 K-1 larger entropy than those in water, respectively, were observed. These values were reasonably explained by the differences in the proton solvation structure in EAN and water. Namely, protons in EAN exist as HNO3 , having a higher reaction energy than that of H3 O+ in water, undergo entropic stabilization as a result of the less-structured solvation. As such, the entropic effect of the proton solvation structure on the acid-base property is possibly applicable to all PILs. In addition, based on these proton thermodynamics, enthalpy and entropy windows were proposed as a novel perspective for the characterization of solvents. Use of this concept enabled the visualization of similarities and differences between EAN and water.
Collapse
Affiliation(s)
- Ryo Kanzaki
- Graduate School of Science and Engineering, Kagoshima University, 1-21-35, Korimoto, Kagoshima, 890-0065, Japan
| | - Hitoshi Kodamatani
- Graduate School of Science and Engineering, Kagoshima University, 1-21-35, Korimoto, Kagoshima, 890-0065, Japan
| | - Takashi Tomiyasu
- Graduate School of Science and Engineering, Kagoshima University, 1-21-35, Korimoto, Kagoshima, 890-0065, Japan
| |
Collapse
|
3
|
Ingenmey J, Gehrke S, Kirchner B. How to Harvest Grotthuss Diffusion in Protic Ionic Liquid Electrolyte Systems. CHEMSUSCHEM 2018; 11:1900-1910. [PMID: 29742320 DOI: 10.1002/cssc.201800436] [Citation(s) in RCA: 40] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/03/2018] [Indexed: 06/08/2023]
Abstract
Hydrogen is often regarded as fuel of the future, and there is an increasing demand for the development of anhydrous proton-conducting electrolytes to enable fuel-cell operation at elevated temperatures exceeding 120 °C. Much attention has been directed at protic ionic liquids as promising candidates, but in the search for highly conductive systems the possibility of designing Grotthuss diffusion-enabled protic ionic liquids has been widely overlooked. Herein, the mechanics of proton-transfer mechanism in the equimolar mixture of N-methylimidazole and acetic acid was explored using ab initio molecular dynamics simulations. The ionicity of the system is approximated with good agreement to experiments. This system consists mostly of neutral species but exhibits a high ionic conductivity through Grotthuss-like proton conduction. Chains of acetic-acid molecules and other species participating in the proton-transfer mechanisms resembling Grotthuss diffusion could be directly observed. Furthermore, based on these findings, a series of static quantum chemical calculations was conducted to investigate the effect of substituting the anion and cation with different functional groups. We predict whether a given combination of cation and anion will be a true ionic liquid or a molecular mixture and propose some systems as candidates for Grotthuss diffusion-enabled protic ionic liquids.
Collapse
Affiliation(s)
- Johannes Ingenmey
- Mulliken Center for Theoretical Chemistry, Universität Bonn, Beringstr. 4, 53115, Bonn, Germany
| | - Sascha Gehrke
- Mulliken Center for Theoretical Chemistry, Universität Bonn, Beringstr. 4, 53115, Bonn, Germany
- Max Planck Institute for Chemical Energy Conversion, Stiftstrasse 3436, 45470, Mülheim an der Ruhr, Germany
| | - Barbara Kirchner
- Mulliken Center for Theoretical Chemistry, Universität Bonn, Beringstr. 4, 53115, Bonn, Germany
| |
Collapse
|
4
|
Himmel D, Radtke V, Butschke B, Krossing I. Grundlegende Bemerkungen zur Azidität. Angew Chem Int Ed Engl 2018. [DOI: 10.1002/ange.201709057] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Affiliation(s)
- Daniel Himmel
- Institut für Anorganische und Analytische Chemie, und Freiburger Materialforschungszentrum (FMF); Universität Freiburg; Albertstraße 21 79104 Freiburg Deutschland
| | - Valentin Radtke
- Institut für Anorganische und Analytische Chemie, und Freiburger Materialforschungszentrum (FMF); Universität Freiburg; Albertstraße 21 79104 Freiburg Deutschland
| | - Burkhard Butschke
- Institut für Anorganische und Analytische Chemie, und Freiburger Materialforschungszentrum (FMF); Universität Freiburg; Albertstraße 21 79104 Freiburg Deutschland
| | - Ingo Krossing
- Institut für Anorganische und Analytische Chemie, und Freiburger Materialforschungszentrum (FMF); Universität Freiburg; Albertstraße 21 79104 Freiburg Deutschland
| |
Collapse
|
5
|
Himmel D, Radtke V, Butschke B, Krossing I. Basic Remarks on Acidity. Angew Chem Int Ed Engl 2018; 57:4386-4411. [PMID: 29171707 DOI: 10.1002/anie.201709057] [Citation(s) in RCA: 39] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/01/2017] [Revised: 11/16/2017] [Indexed: 12/21/2022]
Abstract
This Review provides a unified view on Brønsted acidity. For this purpose, a brief overview of the concepts acidity, acid strengths, and pH value is given, including problems, proposed solutions, and the use of the pHabs /pHabsH2O scale as a unifying concept. Thereafter, some examples of the accessibility and application of unified pHabs values are given. The Review is rounded off with the analogy of acid-base chemistry to redox chemistry with the introduction of the unified redox scale peabs . The combination of pHabs and peabs values in the protoelectric potential map (PPM), as elaborated in ongoing studies on the thermochemistry of single ions, provides a means to classify and to compare all possible acid-base/redox reactions in a medium-independent and, thus, unified fashion.
Collapse
Affiliation(s)
- Daniel Himmel
- Institut für Anorganische und Analytische Chemie and Freiburger Materialforschungszentrum (FMF), Universität Freiburg, Albertstrasse 21, 79104, Freiburg, Germany
| | - Valentin Radtke
- Institut für Anorganische und Analytische Chemie and Freiburger Materialforschungszentrum (FMF), Universität Freiburg, Albertstrasse 21, 79104, Freiburg, Germany
| | - Burkhard Butschke
- Institut für Anorganische und Analytische Chemie and Freiburger Materialforschungszentrum (FMF), Universität Freiburg, Albertstrasse 21, 79104, Freiburg, Germany
| | - Ingo Krossing
- Institut für Anorganische und Analytische Chemie and Freiburger Materialforschungszentrum (FMF), Universität Freiburg, Albertstrasse 21, 79104, Freiburg, Germany
| |
Collapse
|
6
|
Han Q, Wang X, Byrne N. A Simple Approach to Achieve Self‐Buffering Protic Ionic Liquid‐Water Mixtures. ChemistrySelect 2017. [DOI: 10.1002/slct.201700651] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Affiliation(s)
- Qi Han
- Institute for Frontier Materials Deakin University Pigdons Road Waurn Ponds Victoria 3217 Australia
| | - Xungai Wang
- Institute for Frontier Materials Deakin University Pigdons Road Waurn Ponds Victoria 3217 Australia
| | - Nolene Byrne
- Institute for Frontier Materials Deakin University Pigdons Road Waurn Ponds Victoria 3217 Australia
| |
Collapse
|